1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to an image sensor module, which is used in an electronic device, such as a camera phone, a digital camera, etc. More particularly, the present invention relates to an image sensor module having a sensor chip closely adhered on a concave surface, and a fabrication method thereof.
2. Description of the Related Art
Generally, an electronic device, such as a camera phone, a digital camera, etc., has an image sensor module, which can take a photograph of a certain object. The image sensor module requires satisfying conditions including miniaturization, high resolution, and thinness, as well as price competitiveness.
However, a conventional typical image sensor module is configured, so that to calibrate an aberration caused by discordance between a focal plane of lens in the form of a curved surface and a sensor surface of a sensor chip in the form of a plane, a plurality of expensive aspheric lenses lies one upon another. Thus, the conventional image sensor module comes large in whole thickness, does not obtain sufficient high resolution, and causes fabrication costs to increase.
Also, the conventional image sensor module is configured, so that the sensor surface of the sensor chip is formed in the form of the plane. Thus, the conventional image sensor module presents a vignetting phenomenon that as pixels located at an edge of the sensor chip decrease in the intensity of received irradiation, images are become dark. To improve the vignetting phenomenon, some image sensor modules are configured, so that a pixel pitch at the edge of the sensor chip is larger than that at a center of the sensor chip, thereby calibrating the intensity of received irradiation. In this case, however, the image sensor module does not only come large in whole thickness, but also does not act to calibrate the intensity of received irradiation if it is operated to use a zoom function.
To address the problems described above, there recently has been proposed an image sensor module in which a sensor ship is thinned and bent to have a concave shape, thereby allowing the image sensor module to decrease in the number of lens and size and to improve the resolution. If the image sensor module is fabricated in a level of single part, however, it presents a problem in that when bonding the thinned sensor chips on corresponding concave surfaces of a silicon substrate one by one, it is difficult to precisely align the thinned sensor chips with the corresponding concave surfaces. In addition, if the image sensor module is fabricated in a wafer level, it presents a problem in that it is difficult to fabricate the concave surfaces to coincide with a pitch in an array of sensor chips through a conventional machining method and it is difficult or impossible to form metal via interconnections for electrical connection to penetrate the silicon substrate. Also, to bend the sensor chips in a certain curvature, for example, a radius of curvature of 10 mm, the sensor chips should be fabricated very thin, and there is required a separate complicated working apparatus for aligning and bonding the fabricated sensor chips with the corresponding concave surfaces.